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Background— Plasma concentrations of N-terminal pro-B-type natriuretic peptide (NT-proBNP) have been found to predict risk of sudden cardiac death (SCD) in patients with known cardiac disease, and C-reactive protein levels have been found to predict risk among apparently healthy men. However, there are no data on SCD risk prediction for either of these markers in a population of women unselected on the basis of cardiovascular disease.

Methods and Results— In a prospective, nested, case-control analysis within the 121 700-participant Nurses’ Health Study, 99 cases of definite or probable SCD were identified and matched to 294 controls. In multivariable models that adjusted for coronary heart disease risk factors, glomerular filtration rate, and other biomarkers, the trend across quartiles approached significance for NT-proBNP (rate ratio=2.37 for comparison of the highest and lowest quartile; P for trend=0.05) but not for high-sensitivity C-reactive protein (P for trend=0.60). When examined continuously, both NT-proBNP and high-sensitivity C-reactive protein were significantly associated with SCD risk in age- and fasting-adjusted models (P for linear trend=0.04 and 0.03). Adjustment for coronary heart disease risk factors and other biomarkers strengthened the relationship with NT-proBNP and SCD (relative risk for 1-SD increment=1.49; 95% confidence interval, 1.09 to 2.05; P=0.01) but eliminated the relationship with high-sensitivity C-reactive protein (P=0.34). Women with NT-proBNP levels above the prespecified cut point of 389 pg/mL were at a markedly increased risk of SCD in both models (rate ratio=5.68; 95% confidence interval, 1.78 to 18.2; P=0.003).

Conclusions— In this population of women, baseline levels of NT-proBNP were associated with subsequent risk of SCD. If this association is confirmed in larger prospectively studied populations, these findings might provide another useful marker contributing to efforts to screen and prevent SCD among women.

Background: Although cardiac troponin (cTn) is a cornerstone marker in the assessment and management of patients with acute coronary syndrome (ACS) and heart failure (HF), cTn is not diagnostically specific for any single myocardial disease process. This narrative review discusses increases in cTn that result from acute and chronic diseases, iatrogenic causes, and myocardial injury other than ACS and HF.

Content: Increased cTn concentrations have been reported in cardiac, vascular, and respiratory disease and in association with infectious processes. In cases involving acute aortic dissection, cerebrovascular accident, treatment in an intensive care unit, and upper gastrointestinal bleeding, increased cTn predicts a longer time to diagnosis and treatment, increased length of hospital stay, and increased mortality. cTn increases are diagnostically and prognostically useful in patients with cardiac inflammatory diseases and in patients with respiratory disease; in respiratory disease cTn can help identify patients who would benefit from aggressive management. In chronic renal failure patients the diagnostic sensitivity of cTn for ACS is decreased, but cTn is prognostic for the development of cardiovascular disease. cTn also provides useful information when increases are attributable to various iatrogenic causes and blunt chest trauma.

Summary: Information on the diagnostic and prognostic uses of cTn in conditions other than ACS and heart failure is accumulating. Although increased cTn in settings other than ACS or heart failure is frequently considered a clinical confounder, the astute physician must be able to interpret cTn as a dynamic marker of myocardial damage, using clinical acumen to determine the source and significance of any reported cTn increase.

Methods: At the time of 64-slice CT scan, we acquired plasma and serum samples for these biomarkers from 346 patients [mean (SD) age 53 (12) years, 65% men]. Left atrial volume (LAV) and left ventricular volumes at end-diastole (LVEDV) and end-systole (LVESV) were measured and indexed to body surface area (LAVI, LVEDI, LVESI).

Results: Concentrations of both natriuretic peptides were correlated with LAV and LAVI (r = 0.19–0.32, all P ≤ 0.0005) and MR-proADM with LV volumes and indices (r = –0.14 to –0.21, all P ≤ 0.01). NT-proBNP and MR-proANP concentrations were higher in the top quartiles of patients than the lowest quartiles using LAV and LAVI, whereas MR-proADM concentrations were lower in the top quartiles of LV measures. In adjusted analyses, patients had 2- to 4-fold increased risk of LA enlargement for every incremental increase in log10NT-proBNP [LAV odds ratio (OR) 2.4, P = 0.03; LAVI OR 4.0, P = 0.003] and 10- to 13-fold increased risk of LA enlargement for every incremental increase in log10MR-proANP (LAV OR 10.7, P = 0.009; LAVI OR 13.1, P = 0.004).

Conclusions: In patients without heart failure, both NT-proBNP and MR-proANP concentrations are independently associated with LA enlargement, whereas MR-proADM concentrations are correlated with LV volumes. This may partially explain the well-recognized value of natriuretic peptides for use in risk stratification.

Although numerous biomarkers may be prognostically meaningful in patients with acute dyspnea, few comparative analyses have addressed possible associations between a wide range of candidate biomarkers and clinical variables.

METHODS:

Vital status was obtained for 517 acutely dyspneic patients at 4 years after emergency department presentation. A wide array of biomarkers was measured in this cohort, including natriuretic peptides, necrosis markers, inflammatory markers, hematologic markers, and renal markers. We performed statistical evaluation by using minimization of the Bayesian information criterion to evaluate predictors of 4-year mortality. Cox proportional hazards analysis was used to confirm results from the Bayesian information criterion. A final risk model was derived, and this model was then validated by applying it to patients from a separate cohort of acutely dyspneic patients.

RESULTS:

By 4 years, there were 186 deaths (36%). In addition to several clinical variables, several biomarkers were significant predictors of death, including log-transformed concentrations of hemoglobin (hazard ratio=0.77; P < 0.001), soluble ST2 (hazard ratio=1.38; P < 0.001), and amino-terminal pro-B–type natriuretic peptide (hazard ratio=1.19; P < 0.001). Risk models that used these significant variables were accurate in predicting 4-year mortality in both the training and validation sets.